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https://issues.apache.org/jira/browse/ZOOKEEPER-2789?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16288015#comment-16288015
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ASF GitHub Bot commented on ZOOKEEPER-2789:
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Github user phunt commented on the issue:
https://github.com/apache/zookeeper/pull/262
Are you seeing this behavior with ZOOKEEPER-1277 applied? If so it's a bug
in that change, because after that's applied the leader should shutdown as we
approach the rollover.
It would be nice to address this by changing the zxid semantics, but I
don't believe that's a great idea. Instead I would rather see us address any
shortcoming in my original fix (1277)
fwiw - what I have seen people do in this situation is to monitor the zxid
and when it gets close (say within 10%) of the rollover they have an automated
script which restarts the leader, which forces a re-election. However 1277
should be doing this for you.
Given you are seeing this issue perhaps you can help with resolving any
bugs in 1277? thanks!
> Reassign `ZXID` for solving 32bit overflow problem
> --------------------------------------------------
>
> Key: ZOOKEEPER-2789
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2789
> Project: ZooKeeper
> Issue Type: Bug
> Components: quorum
> Affects Versions: 3.5.3
> Reporter: Benedict Jin
> Assignee: Benedict Jin
> Fix For: 3.6.0
>
> Original Estimate: 168h
> Remaining Estimate: 168h
>
> If it is `1k/s` ops, then as long as $2^32 / (86400 * 1000) \approx 49.7$
> days ZXID will exhausted. But, if we reassign the `ZXID` into 16bit for
> `epoch` and 48bit for `counter`, then the problem will not occur until after
> $Math.min(2^16 / 365, 2^48 / (86400 * 1000 * 365)) \approx Math.min(179.6,
> 8925.5) = 179.6$ years.
> However, i thought the ZXID is `long` type, reading and writing the long type
> (and `double` type the same) in JVM, is divided into high 32bit and low 32bit
> part of the operation, and because the `ZXID` variable is not modified with
> `volatile` and is not boxed for the corresponding reference type (`Long` /
> `Double`), so it belongs to [non-atomic operation]
> (https://docs.oracle.com/javase/specs/jls/se8 /html/jls-17.html#jls-17.7).
> Thus, if the lower 32 bits of the upper 32 bits are divided into the entire
> 32 bits of the `long`, there may be a concurrent problem.
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